not sure what database you're using or if these 'default values' would change from time to time depending on context, but
you could let the database take care of that for you. Most DBs will let you assign defaults for columns. I'm an Oracle guy and I do this in a few places and it works like a charm.
obviously, this is only useful if these are true 'defaults' that would always be the same in the absence of real data to insert.

I suggest you write "NULL" to the questioned fields of DataBase if you don't want to insert values and if these aren't required. Though you can continue without big changes. I think this is, what the "NULL" was implemented for. :-)Have a nice dayAll decision is left to your taste